diff mbox

[05/10] drm/syncobj: Add a callback mechanism for replace_fence (v2)

Message ID 1503683548-23548-5-git-send-email-jason.ekstrand@intel.com (mailing list archive)
State New, archived
Headers show

Commit Message

Jason Ekstrand Aug. 25, 2017, 5:52 p.m. UTC
It is useful in certain circumstances to know when the fence is replaced
in a syncobj.  Specifically, it may be useful to know when the fence
goes from NULL to something valid.  This does make syncobj_replace_fence
a little more expensive because it has to take a lock but, in the common
case where there is no callback list, it spends a very short amount of
time inside the lock.

v2:
 - Don't lock in drm_syncobj_fence_get.  We only really need to lock
   around fence_replace to make the callback work.

Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
---
 drivers/gpu/drm/drm_syncobj.c | 60 +++++++++++++++++++++++++++++++++++++++++--
 include/drm/drm_syncobj.h     | 39 ++++++++++++++++++++++++++++
 2 files changed, 97 insertions(+), 2 deletions(-)

Comments

kernel test robot Aug. 27, 2017, 7:34 p.m. UTC | #1
Hi Jason,

[auto build test WARNING on drm/drm-next]
[also build test WARNING on next-20170825]
[cannot apply to v4.13-rc6]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Jason-Ekstrand/drm-syncobj-Rename-fence_get-to-find_fence/20170828-014816
base:   git://people.freedesktop.org/~airlied/linux.git drm-next
reproduce: make htmldocs

All warnings (new ones prefixed by >>):

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>> include/drm/drm_syncobj.h:69: warning: No description found for parameter 'cb_list'
>> include/drm/drm_syncobj.h:69: warning: Excess struct/union/enum/typedef member 'list' description in 'drm_syncobj'
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vim +/cb_list +69 include/drm/drm_syncobj.h

e9083420 Dave Airlie 2017-04-04 @69  

:::::: The code at line 69 was first introduced by commit
:::::: e9083420bbacce27e43d418064d0d2dfb4b37aaa drm: introduce sync objects (v4)

:::::: TO: Dave Airlie <airlied@redhat.com>
:::::: CC: Dave Airlie <airlied@redhat.com>

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation
diff mbox

Patch

diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index 4e8563c..bade497 100644
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -80,6 +80,46 @@  struct drm_syncobj *drm_syncobj_find(struct drm_file *file_private,
 }
 EXPORT_SYMBOL(drm_syncobj_find);
 
+static void drm_syncobj_add_callback_locked(struct drm_syncobj *syncobj,
+					    struct drm_syncobj_cb *cb,
+					    drm_syncobj_func_t func)
+{
+	cb->func = func;
+	list_add_tail(&cb->node, &syncobj->cb_list);
+}
+
+/**
+ * drm_syncobj_add_callback - adds a callback to syncobj::cb_list
+ * @syncobj: Sync object to which to add the callback
+ * @cb: Callback to add
+ * @func: Func to use when initializing the drm_syncobj_cb struct
+ *
+ * This adds a callback to be called next time the fence is replaced
+ */
+void drm_syncobj_add_callback(struct drm_syncobj *syncobj,
+			      struct drm_syncobj_cb *cb,
+			      drm_syncobj_func_t func)
+{
+	spin_lock(&syncobj->lock);
+	drm_syncobj_add_callback_locked(syncobj, cb, func);
+	spin_unlock(&syncobj->lock);
+}
+EXPORT_SYMBOL(drm_syncobj_add_callback);
+
+/**
+ * drm_syncobj_add_callback - removes a callback to syncobj::cb_list
+ * @syncobj: Sync object from which to remove the callback
+ * @cb: Callback to remove
+ */
+void drm_syncobj_remove_callback(struct drm_syncobj *syncobj,
+				 struct drm_syncobj_cb *cb)
+{
+	spin_lock(&syncobj->lock);
+	list_del_init(&cb->node);
+	spin_unlock(&syncobj->lock);
+}
+EXPORT_SYMBOL(drm_syncobj_remove_callback);
+
 /**
  * drm_syncobj_replace_fence - replace fence in a sync object.
  * @syncobj: Sync object to replace fence in
@@ -91,10 +131,24 @@  void drm_syncobj_replace_fence(struct drm_syncobj *syncobj,
 			       struct dma_fence *fence)
 {
 	struct dma_fence *old_fence;
+	struct drm_syncobj_cb *cur, *tmp;
 
 	if (fence)
 		dma_fence_get(fence);
-	old_fence = xchg(&syncobj->fence, fence);
+
+	spin_lock(&syncobj->lock);
+
+	old_fence = syncobj->fence;
+	syncobj->fence = fence;
+
+	if (fence != old_fence) {
+		list_for_each_entry_safe(cur, tmp, &syncobj->cb_list, node) {
+			list_del_init(&cur->node);
+			cur->func(syncobj, cur);
+		}
+	}
+
+	spin_unlock(&syncobj->lock);
 
 	dma_fence_put(old_fence);
 }
@@ -130,7 +184,7 @@  void drm_syncobj_free(struct kref *kref)
 	struct drm_syncobj *syncobj = container_of(kref,
 						   struct drm_syncobj,
 						   refcount);
-	dma_fence_put(syncobj->fence);
+	drm_syncobj_replace_fence(syncobj, NULL);
 	kfree(syncobj);
 }
 EXPORT_SYMBOL(drm_syncobj_free);
@@ -146,6 +200,8 @@  static int drm_syncobj_create(struct drm_file *file_private,
 		return -ENOMEM;
 
 	kref_init(&syncobj->refcount);
+	INIT_LIST_HEAD(&syncobj->cb_list);
+	spin_lock_init(&syncobj->lock);
 
 	idr_preload(GFP_KERNEL);
 	spin_lock(&file_private->syncobj_table_lock);
diff --git a/include/drm/drm_syncobj.h b/include/drm/drm_syncobj.h
index ce94d14..aef7c10 100644
--- a/include/drm/drm_syncobj.h
+++ b/include/drm/drm_syncobj.h
@@ -28,6 +28,8 @@ 
 
 #include "linux/dma-fence.h"
 
+struct drm_syncobj_cb;
+
 /**
  * struct drm_syncobj - sync object.
  *
@@ -43,15 +45,47 @@  struct drm_syncobj {
 	/**
 	 * @fence:
 	 * NULL or a pointer to the fence bound to this object.
+	 *
+	 * This field should not be used directly.  Use drm_syncobj_fence_get
+	 * and drm_syncobj_replace_fence instead.
 	 */
 	struct dma_fence *fence;
 	/**
+	 * @list:
+	 * List of callbacks to call when the fence gets replaced
+	 */
+	struct list_head cb_list;
+	/**
+	 * @lock:
+	 * locks cb_list and write-locks fence.
+	 */
+	spinlock_t lock;
+	/**
 	 * @file:
 	 * a file backing for this syncobj.
 	 */
 	struct file *file;
 };
 
+typedef void (*drm_syncobj_func_t)(struct drm_syncobj *syncobj,
+				   struct drm_syncobj_cb *cb);
+
+/**
+ * struct drm_syncobj_cb - callback for drm_syncobj_add_callback
+ * @node: used by drm_syncob_add_callback to append this struct to
+ *	  syncobj::cb_list
+ * @func: drm_syncobj_func_t to call
+ *
+ * This struct will be initialized by drm_syncobj_add_callback, additional
+ * data can be passed along by embedding drm_syncobj_cb in another struct.
+ * The callback will get called the next time drm_syncobj_replace_fence is
+ * called.
+ */
+struct drm_syncobj_cb {
+	struct list_head node;
+	drm_syncobj_func_t func;
+};
+
 void drm_syncobj_free(struct kref *kref);
 
 /**
@@ -91,6 +125,11 @@  drm_syncobj_fence_get(struct drm_syncobj *syncobj)
 
 struct drm_syncobj *drm_syncobj_find(struct drm_file *file_private,
 				     u32 handle);
+void drm_syncobj_add_callback(struct drm_syncobj *syncobj,
+			      struct drm_syncobj_cb *cb,
+			      drm_syncobj_func_t func);
+void drm_syncobj_remove_callback(struct drm_syncobj *syncobj,
+				 struct drm_syncobj_cb *cb);
 void drm_syncobj_replace_fence(struct drm_syncobj *syncobj,
 			       struct dma_fence *fence);
 int drm_syncobj_find_fence(struct drm_file *file_private,